1. Field of the Invention
The present invention relates to a lens-fitted photo film unit. More particularly, the present invention relates to a lens-fitted photo film unit of which components disposed inside a front cover are visible externally.
2. Description Related to the Prior Art
A lens-fitted photo film unit includes assembled parts including a main body, which is pre-loaded with unexposed photo film and incorporates an exposure unit. The lens-fitted photo film unit is widely used, because photographs can be taken easily, and it can be forwarded to a photo laboratory without difficult operation.
There is an idea of designing appearance of the lens-fitted photo film unit with attractiveness and fashionableness. Although it is general to form a front cover of the lens-fitted photo film unit from black resin with a light-shielding characteristic, the idea suggests a skeleton type of the lens-fitted photo film unit in which the front cover is formed from transparent resin. The main body with a shutter mechanism and a flash unit is partially visible through the front cover externally.
The lens-fitted photo film unit known so far in the art has a structure in which the inner side is shielded from ambient light by the main body and the front cover and a rear cover both covering the main body. If the front cover becomes transparent either fully or partially, ambient light is likely to enter a space for movement of a shutter blade between a lens holder and an exposure tunnel for an exposure light path. It is also likely that ambient light enters the main body between engaged portions of a roll holder chamber of the main body and the rear cover, as the front cover is transparent and does not shield light itself at those engaged portions.
If ambient light enters the lens-fitted photo film unit through a gap between the lens holder and the exposure tunnel or between the roll holder chamber and the rear cover, the unexposed photo film is likely to be fogged, and cannot keep quality suitable for good photographing.
In view of the foregoing problems, an object of the present invention is to provide a lens-fitted photo film unit in which a front cover is transparent and also the image quality of photographs to be taken can be kept without influence of ambient light.
In order to achieve the above and other objects and advantages of this invention, a lens-fitted photo film unit includes a main body. A cassette holder chamber is formed in the main body, for containing a photo film cassette. A roll holder chamber is formed in the main body, for containing a roll of photo film drawn from the photo film cassette. A front cover is formed from transparent resin at least partially, for covering a front side of the main body. A rear cover covers a rear side of the main body. The roll holder chamber has a top wall portion and an end wall portion, the end wall portion being disposed farther from the cassette holder chamber. A first light-shielding ridge is disposed to project forwards from the rear cover and to extend horizontally, overlapped with the top wall portion, for blocking entry of ambient light at the top wall portion. A second light-shielding ridge is disposed to project forwards from the rear cover and to extend vertically, overlapped with the end wall portion, for blocking entry of ambient light at the end wall portion, the second light-shielding ridge extending to the first light-shielding ridge.
Furthermore, a first end cover portion is formed to project from the front cover, and disposed outside the end wall portion. A second end cover portion is formed to project from the rear cover and to extend along an outside of the second light-shielding ridge, disposed outside the end wall portion, for covering the end wall portion with the first end cover portion.
Furthermore, an auxiliary ridge portion is formed to project from the rear cover and to extend along a top of the first light-shielding ridge, and overlapped with a top of the top wall portion.
Furthermore, an auxiliary ridge portion is disposed inside the roll holder chamber to extend along an inside of the end wall portion, and opposed to the second light-shielding ridge.
In a preferred embodiment, the cassette holder chamber has a second top wall portion and a second end wall portion, the second end wall portion being disposed farther from the roll holder chamber. Furthermore, a third light-shielding ridge is disposed to project forwards from the rear cover and to extend horizontally, overlapped with the second top wall portion, for blocking entry of ambient light at the second top wall portion. A fourth light-shielding ridge is disposed to project forwards from the rear cover and to extend vertically, overlapped with the second end wall portion, for blocking entry of ambient light at the second end wall portion, the fourth light-shielding ridge ex-ending to the third light-shielding ridge.
In a further preferred embodiment, an exposure light path is formed through the front cover and the main body, for introducing object light to the photo film. A light-shielding member blocks entry of ambient light into the exposure light path through portions of the front cover outside the exposure light path.
The light-shielding member is opaque and has a dark color.
The main body includes an exposure tunnel through which the exposure light path extends. A shutter opening is formed in front of the exposure tunnel, for constituting the exposure light path. A shutter blade is disposed in front of the exposure tunnel in a pivotally movable manner, for providing the photo film with an exposure by opening and closing the shutter opening. A lens holder plate is disposed behind the front cover, for covering the shutter blade. A holder opening is formed in the lens holder plate, for constituting the exposure light path. The light-shielding member comprises a light-shielding ridge formed to project rearwards from an edge of the lens holder plate.
Furthermore, a taking lens is fitted at the holder opening, for focusing the object light on the photo film.
Furthermore, an electronic flash unit illuminates a photographic field with flash light. A synchro switch is disposed between the exposure tunnel and the lens holder plate, for turning on the flash unit upon actuation of the shutter blade.
According to another aspect of the present invention, a taking lens is disposed in front of the main body. A lens opening is formed in the front cover in front of the taking lens, for introducing object light to the taking lens. A blocking member is disposed inside an edge of the lens opening, for blocking advance of ambient light from the front cover to the taking lens outside a predetermined incident angle range.
The blocking member is opaque and has a dark color.
Furthermore, a lens holder plate is disposed between the main body and the front cover, for supporting the taking lens. A lens retainer plate is disposed between the lens holder plate and the front cover, for keeping the taking lens on the lens holder plate. A first opening is formed in a middle of the lens retainer plate, for introducing the object light to the taking lens. The blocking member is formed with the lens retainer plate and disposed between the edge of the lens opening and an edge of the first opening.
The blocking member is a ring-shaped projection projecting from the lens retainer plate and inserted in the lens opening.
A front end of the blocking member is disposed behind a front surface of the front cover.
In still another preferred embodiment, the lens retainer plate keeps the taking lens on the lens holder plate by being sandwiched with the taking lens between the front cover and the lens holder plate.
A front end of the blocking member is disposed in front of a front surface of the front cover.
The blocking member comprises a ring-shaped plate portion. The lens retainer plate includes an outer projection portion disposed to project rearwards from an outer edge of the ring-shaped plate portion. A flange is disposed to project from the outer projection portion away from the first opening, for contacting a rear of an edge of the lens opening. An inner projection portion is disposed to project rearwards from the first opening, for contacting a periphery of the taking lens.
Furthermore, at least one combination of a projection and a recess, of which one is formed in the lens retainer plate and a remainder is formed in the rear of the edge of the lens opening, and which are engaged with each other for retention thereof.